defmodule VavPipeline.MannaLedgerTest do
  @moduledoc """
  Tests for the MannaLedger — manna consumption and anti-hoarding enforcement.

  Shemot 16:4 — D'var yom b'yomo — the day's matter in its day.
  Shemot 16:19 — Al yoter mimenu ad boker — do not leave surplus.
  Shemot 16:20 — Vayotiru... vayarum tola'im vayiv'ash — hoarded manna rots.
  """

  use ExUnit.Case, async: false

  alias VavPipeline.MannaLedger

  setup do
    MannaLedger.reset()
    :ok
  end

  # Helper to load provision from a test fixture file
  defp write_test_provision(opts \\ []) do
    today = Date.utc_today() |> Date.to_iso8601()
    compute = Keyword.get(opts, :compute_units, 100)
    api_calls = Keyword.get(opts, :api_calls_external, 50)
    panels = Keyword.get(opts, :sanhedrin_panels_max, 3)
    type = Keyword.get(opts, :type, "regular")

    expires =
      DateTime.utc_now()
      |> DateTime.add(6 * 3600)
      |> DateTime.to_iso8601()

    provision = %{
      "date" => today,
      "provision" => %{
        "compute_units" => compute,
        "memory_mb" => 1024,
        "api_calls_external" => api_calls,
        "storage_delta_mb" => 10,
        "sanhedrin_panels_max" => panels
      },
      "type" => type,
      "expires_at" => expires,
      "written_by" => "test",
      "written_at" => DateTime.utc_now() |> DateTime.to_iso8601()
    }

    path = VavPipeline.Manna.provision_file()
    File.mkdir_p!(Path.dirname(path))
    File.write!(path, Jason.encode!(provision))

    on_exit(fn -> File.rm(path) end)
    :ok
  end

  # ============================================================
  # Loading provision — d'var yom b'yomo
  # ============================================================
  describe "load_provision" do
    test "loads provision from manna file" do
      write_test_provision(compute_units: 200, api_calls_external: 100)
      assert {:ok, :loaded} = MannaLedger.load_provision()

      ledger = MannaLedger.ledger()
      assert ledger.allocated.compute_units == 200
      assert ledger.allocated.api_calls_external == 100
      assert ledger.consumed.compute_units == 0
    end

    test "returns :already_loaded if same day" do
      write_test_provision()
      assert {:ok, :loaded} = MannaLedger.load_provision()
      assert {:ok, :already_loaded} = MannaLedger.load_provision()
    end

    test "returns :no_provision when no manna file" do
      # Ensure provision file doesn't exist
      path = VavPipeline.Manna.provision_file()
      File.rm(path)

      assert {:ok, :no_provision} = MannaLedger.load_provision()
    end
  end

  # ============================================================
  # Consumption — v'laktu d'var yom b'yomo
  # ============================================================
  describe "consume" do
    setup do
      write_test_provision(compute_units: 10, api_calls_external: 5, sanhedrin_panels_max: 2)
      MannaLedger.load_provision()
      :ok
    end

    test "consumes resource and returns remaining" do
      assert {:ok, 7} = MannaLedger.consume(:compute_units, 3)
      assert {:ok, 4} = MannaLedger.consume(:compute_units, 3)
    end

    test "rejects when resource exhausted" do
      MannaLedger.consume(:compute_units, 10)
      assert {:error, :provision_exhausted} = MannaLedger.consume(:compute_units, 1)
    end

    test "rejects when amount exceeds remaining" do
      MannaLedger.consume(:compute_units, 8)
      assert {:error, :provision_exhausted} = MannaLedger.consume(:compute_units, 5)
    end

    test "different resources tracked independently" do
      MannaLedger.consume(:compute_units, 5)
      MannaLedger.consume(:api_calls_external, 3)

      assert MannaLedger.remaining(:compute_units) == 5
      assert MannaLedger.remaining(:api_calls_external) == 2
    end

    test "returns error when no provision loaded" do
      # Force a fresh cycle by enforcing boundary first
      MannaLedger.enforce_cycle_boundary()

      # Now no provision is loaded
      assert {:error, :no_provision} = MannaLedger.consume(:compute_units, 1)
    end
  end

  # ============================================================
  # Remaining and available?
  # ============================================================
  describe "remaining and available?" do
    setup do
      write_test_provision(compute_units: 20)
      MannaLedger.load_provision()
      :ok
    end

    test "remaining returns correct balance" do
      assert MannaLedger.remaining(:compute_units) == 20
      MannaLedger.consume(:compute_units, 7)
      assert MannaLedger.remaining(:compute_units) == 13
    end

    test "available? checks sufficiency" do
      assert MannaLedger.available?(:compute_units, 20)
      assert MannaLedger.available?(:compute_units, 1)
      refute MannaLedger.available?(:compute_units, 21)

      MannaLedger.consume(:compute_units, 15)
      assert MannaLedger.available?(:compute_units, 5)
      refute MannaLedger.available?(:compute_units, 6)
    end
  end

  # ============================================================
  # Cycle boundary enforcement — al yoter mimenu ad boker
  # ============================================================
  describe "enforce_cycle_boundary" do
    setup do
      write_test_provision(compute_units: 100, api_calls_external: 50)
      MannaLedger.load_provision()
      :ok
    end

    test "releases surplus and zeroes allocation" do
      MannaLedger.consume(:compute_units, 30)
      MannaLedger.consume(:api_calls_external, 10)

      {:ok, %{released: released}} = MannaLedger.enforce_cycle_boundary()

      # 100 allocated - 30 consumed = 70 released
      assert released.compute_units == 70
      # 50 allocated - 10 consumed = 40 released
      assert released.api_calls_external == 40
    end

    test "after enforcement, all resources are zero" do
      MannaLedger.consume(:compute_units, 50)
      MannaLedger.enforce_cycle_boundary()

      assert MannaLedger.remaining(:compute_units) == 0
      assert MannaLedger.remaining(:api_calls_external) == 0
    end

    test "after enforcement, consume returns :no_provision" do
      MannaLedger.enforce_cycle_boundary()
      assert {:error, :no_provision} = MannaLedger.consume(:compute_units, 1)
    end

    test "full consumption leaves nothing to release" do
      MannaLedger.consume(:compute_units, 100)
      MannaLedger.consume(:api_calls_external, 50)

      {:ok, %{released: released}} = MannaLedger.enforce_cycle_boundary()
      assert released.compute_units == 0
      assert released.api_calls_external == 0
    end

    test "enforcement records timestamp" do
      MannaLedger.enforce_cycle_boundary()
      ledger = MannaLedger.ledger()
      assert ledger.last_enforcement != nil
    end
  end

  # ============================================================
  # Manna.enforce_anti_hoarding integration
  # ============================================================
  describe "Manna.enforce_anti_hoarding integration" do
    setup do
      write_test_provision(compute_units: 50)
      MannaLedger.load_provision()
      :ok
    end

    test "Manna.enforce_anti_hoarding delegates to ledger" do
      MannaLedger.consume(:compute_units, 20)
      assert :ok = VavPipeline.Manna.enforce_anti_hoarding()

      # After enforcement, resources are zeroed
      assert MannaLedger.remaining(:compute_units) == 0
    end
  end

  # ============================================================
  # Ledger state
  # ============================================================
  describe "ledger state" do
    test "tracks cycle count" do
      write_test_provision()
      initial = MannaLedger.ledger().cycle_count

      MannaLedger.load_provision()
      assert MannaLedger.ledger().cycle_count == initial + 1

      # Force new cycle
      MannaLedger.enforce_cycle_boundary()

      # Can't easily test second load on same day since it returns :already_loaded
      # But cycle_count incremented on load
    end
  end
end